RANDOMLY AMPLIFIED POLYMORPHIC DNA USING THE M13 CORE SEQUENCE OF THEVESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI GIGASPORA-MARGARITA AND GIGASPORA-GIGANTEA

Vesicular-arbuscular mycorrhizal (VAM) fungi are obligate symbionts, a nd a primary benefit provided to the host is the alleviation of stress . The recalcitrance of these fungi to grow in pure culture has spurred researchers to develop an alternative form of cultivation, namely the root organ culture (ROC). This synthetic form of production is new an d efforts were made to use randomly amplified polymorphic DNA with the M13 minisatellite sequence as the polymerase chain reaction primer to look into polymorphism, if any, in the spores of Gigaspora margarita produced both in vitro and in situ (soil). The fingerprint patterns ob tained from in vitro and in situ spores were similar. Extramatrical st ructures, such as auxiliary cells, were also examined by DNA fingerpri nting. Their amplification pattern did not vary from the mother or dau ghter spores. A few interesting observations were made. For instance, the mother spore, which seemed hollow and inactive after germination, nevertheless contained nuclei after 4 months under in vitro conditions and generated a fingerprint pattern. The fingerprint pattern for Giga spora margarita was different from that of Gigaspora gigantea, indicat ing that the minisatellite sequence could be exploited for identifying VAM fungi. ROC appears to be a truly representative system, in the se nse that it mimics the essential features of the complex rhizosphere, allowing the fungi to complete their life cycle without any induced ge netic changes per se.